1-Question:
 How do I tell if I need a new nut?
 How do I tell if the nut needs adjusting?

   First thing to do is take a good look at the nut.
Are there any chipped places that might cause intonation
or tuning problems? Basically all the strings need to
break contact at the exact front edge of the nut.
To check the string/nut adjustment (the depth of the
string slots) press the string you are checking immediately
in front of the the second fret and tap the string between
the second fret and the nut over the first fret.
This space between the top of the first fret and the bottom
of the string is of critical importance. Too much clearance
and fretting that bar F is hard to do....too little and you'll
get string buzz when you play an open string. String buzz on
an open string is almost always caused by the slot being cut
too low..the other cause would be a loose first fret that has
popped up a bit. So obviously this is not where you go to
lower your overall action. I like to see a little bit of air
here...and hear a nice plink when I tap the string. More room
is needed by the big wound strings than the little plain
unwound ones. A few thicknesses of ordinary paper makes a good
gauge if you don't trust your senses yet. You're just looking
for enough clearance for the string to vibrate plus a little
for wear.

2-Question:
 How can I tell if my neck needs adjusting?

OK, we'll check the neck for straightness. For this procedure
you'll need a good straightedge. Fortunately you already have
one readily available. A tuned string is about as straight as
you can get. Place a capo on the strings just behind the first
fret and tighten only enough to make all the strings contact
the first fret. No need to overtighten. Depress the sixth string
(or whichever string you are checking)just above the fret
closest to where the neck joins the body. Now you have a straight
line with which to compare your neck. We are looking at the air
gap between the bottom of the string and the top of the frets
in the seventh to ninth fret area. On the large strings we need
to see from .010" to .020"....less on electrics, more on
acoustics, less for a soft playing style or fingerpicking, more
for heavy picking. For a gauge you can use a standard matchbook
cover,usually around .015". Due to the circular movement of a
plucked string there has to be some clearance here. A perfectly
straight neck does not play well. On the first string side you
can get away with less clearance. A well made neck with good
fretwork will gradually go from around .015" under the sixth
string to almost no clearance under the first string. Adjustable
truss rods are supposed to compensate for string tension on the
neck and allow you to maintain proper clearances.

3-Question:
 How do I check my action height?
 How do I tell if my action needs adjusting?

  Once the nut adjustment and neck bow are checked we move on
to the actual string height adjustment. This adjustment is made
at the bridge. Check the space between the bottom of the strings
and the top of the twelfth fret. For this I like to use a small
ruler marked in 1/32 or 1/64 inch increments. You can usually
find these at hardware stores, etc. Once again playing style has
a lot to do with your action height. A fairly low action on an
acoustic will be around 3/32" under the sixth string gradually
diminishing to 2/32" under the first string. You'll need more
clearance for heavier playing styles. On electrics 2/32" all the
way across does well for most players.
Obviously the nut and neck relief need to be right before the
last action height adjustment is made. Also keep in mind that
all measurement recomendations are not written in stone and small
variances either way to better suit your own individual style
are to be considered. Once you have your action down to something
reasonable you may notice a string buzz or rattle on some frets.
This means you have some frets that are higher or lower, possibly
loose frets, etc. A good fret leveling and crowning are called
for to correct this. The frets are leveled with a file or stone
while the neck is as straight as possible and then a crowning file
is used to put a nice crown on the frets so the string breaks in
the center if the fret when depressed. Then the above setup
procedure is followed making any adjustments necessary. For those
of you wanting to do your own setup work please look for the
articles on making neck adjustments and dressing frets.
 

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